This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 30 |
| 4 | 264 |
| 5 | 7320 |
| 6 | 30960 |
| 7 | 1592640 |
| 8 | 38183040 |
| 9 | 394450560 |
| 10 | 2238969600 |
| 11 | 275106585600 |
| 12 | 4038941491200 |
| 13 | 689773321036800 |
| 14 | 20996629900646400 |
| 15 | 111964387062528000 |
| 16 | 2210304446558208000 |
| 17 | 642338416210563072000 |
| 18 | 19249748121316737024000 |
| 19 | 6980209591900198477824000 |